Reproduction in Organism
Biology
Q/A
1. Why are humans called unisexual animals?
Ans: Animals which has different reproductive organs for male and female for reproduction are called unisexual animal. In human, male and female has different reproductive organs. For this reason human is called unisexual animal.
2. What is the uterus? What is its function?
Ans: Uterus, also called womb, an inverted pear-shaped muscular organ of the female reproductive system, located between the bladder and the rectum. It functions to nourish and house a fertilized egg until the fetus, or offspring, is ready to be delivered.
3. What is the placenta? What are the functions of the placenta?
Ans: The special organ through which the fetus in the uterus is connected to the tissue of the mother is called the placenta.
Functions of the placenta:
a) Allows dissolved food substances ( e.g. glucose, amino acids, minerals salts) and O2 to diffuse from the mother's blood into that of the embryo.
b) Allows metabolic waste products (e.g. urea and CO2) to diffuse from the embryonic blood capillaries into the mother's bloodstream.
c) Allows antibodies to diffuse from the mother's blood into the embryonic blood capillaries. The antibodies protect the embryo against certain diseases.
d) Produces progesterone which maintains uterine lining in healthy state during pregnancy.
4. What measures should be taken to prevent AIDS?
The following measures must be taken to prevent AIDS:
a. Following the religious rules and obeying the ideals set by the society for our character and attitude.
b. Having trust on only one life partner sexual relation only with one sexual partner.
C. The prior checking of HIV, before taking blood from any donor or source.
D. Avoid using the needles, blade and syringe of others.
E. Creating awareness amongst all people including adolecents.
F. Using disinfected scissors and needles while piercing ear, nose or skin of boy.
G. Taking steps with cautions while transplanting organ in our body.
H. Taking special precautions while going abroad or non- residents.
I. Engaging youth in mass awareness program to prevent AIDS.
5. Explain the functions of hormones in reproduction.
Ans: The Growth stimulating hormone and producing hormone are produced by the pituitary gland. These hormones regulate growth of reproductive glands secretion and control the functions, controls mammary gland and milk secretes thyroxine hormone. It regulates metabolic function ensures physical and mental development, sexual characteristics. Testosterone hormone secreted from testis and androgen helps to produce sperms and sexual secondary characteristics, such as: deepening of voice and growth of beard.
The Ovary secretes estrogen, progesterone, relaxin hormones. These hormones cause the development of sexual characteristics, such as menstruation, enlargement of the wall of uterus for implantation of the embryo and placenta. Besides this it has a particular role in the formation of ovum. Gonadotropic and progesterone of placenta stimulates ductless glands of the ovary and helps in enlargement of mammary glands.
6. Why is a flower called the reproductive organ?
Ans: A flower is a reproductive organ of a higher plant. We know that the two ( androecium and gynoecium) of the whorls of a flower are very significant for reproduction. Though other parts or whorls of flower do not directly take part in reproduction, they meaningfully help the process reproduction. The flowers, which have five whorls, are called complete flowers. If a flower lacks any of the five whorls, it is called an incomplete flower. When both androecium and the gynoecium are present in a flower, it is called a bisexual flower. If any of the whorls androecium or gynoecium is absent, this flower is called unisexual flower. If both androecium and gynoecium are absent in any flower, it is called a neuter flower.
7. Describe the causes, symptoms and remedies of AIDS.
Ans: Causes of AIDS:
A healthy person can be infected by this life-threatening disease in the following ways:
Symptoms of AIDS:
Remedies of AIDS -
a) Learn more about HIV to actively share in health care decisions.
b) Join a support group to share information and emotions relating to HIV.
c) Practice safer sex. Use condoms whenever you have sex.
d) Learn how to handle food safely so you don't get a food-borne infection.
e) Eat a healthy diet, get regular exercise, don't smoke, and don't use illegal drugs.
f) Get immunizations as needed.
Multiple-choice questions
1. In which flower, are the stamens diadelphous (that is filaments of stamens are united in two bundles)?
a. Chinese hibiscus
b. Pees
c. Cotton tree or shimul
d. Sunflower
2. The air pollinated flower is -
i. large in size
ii. with undivided stigma
iii. without nectar glands
Which one is correct?
a. i & ii
b. i & iii
c. ii & iii
d. i , ii & iii
Look at the stem and answer the questions 3 and 4:
3. Which part of the stem turns into a seed?
a. N
b. O
c. P
d. Q
4. Which one does play a role in producing endosperm?
a. M & Q
b. M & P
c. M & N
d. N & P
Creative Questions
1. a. What is an embryo sac?
Ans: An Androecium a sac-like apical structure is called an embryo sac.
b. What is indefinite inflorescence?
Ans: We have seen clusters of flower arranged in a small branch of a tree, following some special orders of arrangement is called inflorescence. Along with the flowers, the branch of a tree is called inflorescence. It is called peduncle on which flowers are orderly arranged. If the growth of the axis is unlimited, it is called indefinite inflorescence. Example - Inflorescence of mustard.
c. Explain the problems there will be in pollination if the part P is absent.
Ans: The P part of the figure is known as androecium. Every part of an androecia is called stamen. In the head of stamen there is a embryo sac. Pollens are developed in an anther which is important for pollination. If P part is not present in flower then the problems.
i. In the flower in figure self- pollination is not possible. Cross pollination is possible.
ii. Because of the absence of the pollination of the flower depends on the medium.
iii. Because of not having P part in the flower, the purity of species is impaired.
iv. Pollination may not be ensured.
V. During this type of pollination, waste of pollens will be occurred.
Vi. Because of these, new varieties will emerge.
Vii. Because of not having P part, adaption capability is increased.
d. Explain your opinion how part Q serves its species.
Ans: The Q part is known as Gynoecium. It is an essential whorl of a flower. There is ovule present in the gynoecium. Within the ovule, female reproductive cell ovum is produced. This ovum like an androecium directly gets involved in the process reproduction. In the ovum there exists female gamete. After pollination female gamete mixing with a male gamete produces zygote. Another male gamete mixing with the secondary nuclei develop triploid cells. Because of this fertilized gynoecium and fertilized ovum we get seeds and from seeds we get plants. In this way part Q in the stem serves its own species.
2. 12 years old Ridoy sings with a melodious voice. Recently with some physical and mental changes, his voice becomes deep. So, his mother consulted with a doctor, who said, this change is normal for children.
a. What is the placenta?
Ans: A particular organ built up of material and fetus tissue forms a connection jointly is called placenta.
b. Why is AIDS called a fatal disease?
Ans: Full name of 'AIDS' is Acquired Immune Deficiency Syndrome. AIDS disease is caused in human body by the attack of one kind of virus named HIV - Human Immune Deficiency Virus. This virus destroys white blood cells causes obstacle in antibody formation, that results the gradual shortage white blood cell and antibody. The HIV virus destroys the victims immune system. That's why it is called fatal disease.
c. Explain the causes of the events happened in Ridoy's body.
Ans: In our human body there are different types of hormones which play an important role to control our growth, the shape of our body even they are responsible for the change in our voice. Along with physical growth, reproductive system also grows and develops with the increasing of age. Hormones play a significant role in this process. Children pass over their childhood adolescence and attain youth. The transitional period adolescence and attain youth. The transitional period adolescence indolence and the youth is named as puberty.
In the stem Ridoy is 12 years old. The cause of his physical and mental change is his puberty. In this period thyroid gland secretes thyroxin hormone which regulates metabolic function, ensures physical and mental development. Testosterone hormone secreted from testis and androgen helps to produce sperms and sexual secondary characters such as deepening of voice. So, these hormones are the cause of events happened in Ridoy's body.
d. Explain the role of the elders towards Ridoy.
Ans: Ridoy is now puberty stage. In this stage, different types of hormones are secreted from endocrine gland and they bring different types of physical and mental changes. This also brings change in behaviour. All these things happened to Ridoy also. In this case the role of the elders towards Ridoy should be-
i. Elders should make him realize about his change
ii. Behave well with him
iii. Teach him not to take the bad ways
iv. Make him realize how to face this change and lead a life in good way.
Q.1. What is reproduction?
Ans: Reproduction is a physiological activity through which organisms continue existence by producing offspring (babies).
Reproduction 2 types-
Asexual
sexual
Q.2. What is gamete?
Ans: A gamete is a reproductive cell containing the haploid number of chromosomes.
Q.3. What is puberty?
Ans: Puberty is a time of active growth in humans during which the person changes from a child to an adult. During this time, the reproductive system of the person begins to function properly.
Q.4. What is menstrual cycle?
Ans: For the girl, the first sign of puberty is usually the monthly discharge of blood from the uterus via the vagina. This is called menstruation. Every month, a cycle of events takes place in the female reproductive organs. This is called the menstrual cycle.
Q.5. How does hormonal control of the menstrual cycle?
Ans: The cycle of events taking place in the ovary is controlled by hormones secreted by the anterior pituitary gland.
The cycle begins with the onset of menstruation. The anterior lobe of the pituitary gland secretes follicle-stimulating hormone into the bloodstream.
FSH stimulates the development of the follicles in the ovaries. Usually one follicle ripens to become the Graafian follicle in one of the ovaries during each cycle.
After menstruation, it causes the repair and growth of the uterine lining. The uterine lining becomes thick and spongy with blood vessels.
It stimulates the pituitary gland to secrete luteinising hormone and causes ovulation and also causes the formation of the corpus luteum.
The corpus luteum secrets progesterone and also some oestrogen.
Progesterone keeps the uterine lining thick and well supplied with blood, preparing it for the implantation of the embryo.
Q/A
1. What is pollination? Describe the types of pollination.
Ans: The transfer of pollen from the anther to the stigma of the same flower or to the stigma of another plant of the same species is pollination.
Pollination is two types -
a) Self- pollination :
On the same flower or on two flowers of the same plant, transfer of pollen can occur. This is called self-pollination. For example - brassica, cucumber and datura.
b) Cross- pollination:
When the attachment of pollen occurs in between two distinct flowers of the same species, it is called cross-pollination, such as, cotton tree (Salmalia malabarica), papayas (Carica papaya).
Q.2. Explain about the medium of pollination.
2. Describe the different parts of a flower.
Ans: Different parts of a flower -
a) Thalamus:
This is usually round and is developed at the tip of a floral axis.
b) Calyx:
The outermost whorl of a flower is called the calyx. Each of the part of calyx is called a sepal.
Function:
i) Save the inner parts of a flower from the sun, rain and attack of insects and pests.
ii) Colourful calay plays important roles in pollination.
c) Corolla:
It is the outermost but one whorl of a flower. If the corolla is segmented, each segment is then called a petal.
Function:
i) They protect the internal parts of a flower from the sun and rain.
ii) Bright colourful corolla attract animals - birds, insects etc. and helps pollination.
d) Androecium:
It is the third whorl from outside of a flower, and it is an essential whorl. Every part of an androecium is called a stamen. The stalk like structure of stamen is called the filament and the sac like apical structure of it is called the anther.
Function :
i) Pollens are developed in an anther.
ii) A pollen tube is produced from a pollen after germination.
e) Gynoecium:
The gynoecium is at the centre of a flower. A gynoecium may be structured with one or more carpels. A carpel has three parts - ovary, style and stigma. One or more ovules are in a flower, arranged inside of the ovary.
Function:
Within the ovule, the female reproductive cell is produced. This ovum, like an androecium, is directly involved in the process of reproduction.
Q.4. What is the difference between microsporogenesis and megasporogenesis?
Ans: Microsporogenesis:
A pollen is the first cell of a gametophyte. Pollen mother cell (2n) produces four pollen (n) by meiosis. Soon after becoming mature harbouring in the pollen sac starts to germinate. The nucleus of the pollen gets divided through mitotic division and two cells, one large and another small are formed. The large one is turning into the pollen tube and two male gametes are produced. Division of the generative cell takes place in the pollen or pollen tube.
Microsporogenesis:
Near the micropyle, being nourished in the nucellus of the ovule, a cell starts to become larger. Its protoplasm is dense and the nucleus is comparatively large. The cell divides (https://www.educatorsharmin.com/2021/05/biology-for-class-9-and-10-ch-3.html ) into four haploid cells through meiotic division. Every cell, except the smallest one, gets disintegrated. Growing gradually, the larger cell matures into an embryo sac. The nucleus of the cell is a haploid. The nuclei are evolved as the nucleus divides. These two nuclei take positions in two opposing poles. Next, these two nuclei consecutively divide twice and result in four nuclei.
In the next stage, two nuclei from the two poles come to the middle of the cell and get fused to cause the emergence of two haploid secondary nuclei. The nuclei in the two poles turn into cells with some amount of cytoplasm. Collective, the combined structure of the three cells near the micropyle is called the egg apparatus. In between the cells, the one occupying the middle place is the ovum, which is a little larger. This is called an egg cell and the other two are called synargid cells. The cells in the opposite pole to the egg apparatus are called antipodal cells. This is now the process of developing the embryo sac is done.
